Carbureter.



W. SHAKESPEARE, JR- & W. SCHMID. CARBURETER.

APPLICATION FILED NOV. 27.19l5.

IL,%3%,%E Patented July 24, 1917 3 SHEETSSHEET I.

" ATTORNEYS.

W. SHAKESPEARE, JR. & W. SCHMID.

CARBURETER.

APPLICATION FILED NOV. 27. I915.

Patented July 24, 1917.

3 SHEETSSHEET 2.

QS QL W. SHAKESPEARE, .IR- ,& W. SCHMID.

' CARBURETER.

APPLICATION FILED NOV. 27. 1915- LQMEAUE Q Patented July 24, 1917.

3 SHEETS-SHEET 3.

a: i as rattan nib.

WILLIAM SHAKESPEARE, JB., AND WILLIAM SCHMID, OF KALAMAZOO, MICHIGAN, ASSIGNORS 'IO SHAKESPEARE COMPANY, OF KALAIVIAZOO, MICHIGAN.

CARIBURETER.

manner.

Specification of Letters Patent. Patfijantedl July 24's, llgill'iw Application filed November 27, 1915. Serial No. 63,747.

To all whom it may concern:

. Be it known that we, WILLIAM SHAKE- SPEARE, Jr., and WILLIAM SGHMID, citizens of the United States, residing at Kalama- Zoo, Michigan, have invented certain. new and useful Improvements in Garbureters, of which the following is a specification.

This invention relates to improvements in carbureters.

Our present improvements relate particularly to the type of ca-rbureter shown in our application for Letters Patent filed December 11, 1914, Ser. No. 876,626, and our application for Letters Patent, filed October 2, 1915, Ser. No. 53,747, and are an embodiment of and in some respects an improvement upon the structures illustrated therein. Certain features of our present improvements are, however, of quite general application and capable of being readily embodied in structures which vary considerably from those illustrated in our said applications. I

The main objects of our invention are:

To provide an improved carbureter' in which proper relative proportions of "fuel and air are automatically retained throughout varying running conditions of the engine and throughout the scope of the throttle adjustment.

Further objects,- and objects relating to structural details, will definitely appear from the detailed description to follow.

. We accomplish the objects of our invention by the devices and means described in the following specification. The invention is clearly defined and pointed out in'' the claims.

A structure which is a preferred embodiment of our invention is clearly illustrated in the accompanying drawing forming a part of this specification, inwhich: Figure I is an end view of our improved carbureter looking from the right of Fig. II, the primer and air inlet valve operating connections being shown in detail in connection therewith. v v

Fig. II is a side view of our improved carbureter looking from the left of Fig. I.

Fig. III is a vertical central section on a p line corresponding to line 3-3 of Figs. I

and IV, parts being shown in full lines for ing to line 5-5 of Fig. IV.

Fig. VI is a detail vertical section on a.

' line corresponding to line 66 of Fig..III,

showing details of the primer valve and cold air inlet valve connections.

Fig. VII is a detail vertical section on a line corresponding to line 7-7 of Fig. III, showing details of the primer valve stop.

Fig. VIII is a detail horizontal section on a line corresponding to line 8-8 of Fig. III, showing details of the auxiliary air inlet valve.

Fig. IX is a detail of the air inlet and primer actuating lever with the face plate of the housing removed.

Fig. X is a horizontal section on a line corresponding to line 10-10 of Figs. I and IX.

Fig. XI is a detail section on a line corresponding to line 1111 of Fig. IX.

'Fig. XII is a plan view of the attaching strap for the adjusting lever housing.

Fig. XIII is a front view of a modified form of the air inlet valve and primer actuating lever.

Fig. XIV is a detail section 'on a line corresponding to line 1414 of Fig. XIII.

In the drawing similar reference characters refer to similar parts throughout the severaLviews, and the sectional views are taken looking in the direction of the little arrows at the ends of the section lines.

Referring to the drawing, the body of our improved carbureter consists of an intermediate body member 1 having a peripheral flange-like side wall portion 2 and a central depending tubular portion 3. A top body member 4 adapted to fit upon the up per edge of the side wall portion 2 of the intermediate body member 1 is provided.

These members or sections 1 and 4 are se-' screws being arranged through the body member 4, thus avoiding the necessity for being provided with a stem 21 ceive the screws.

vided with an air mouth or nipple 8 to a means for supplying heated air (the means not being illustrated) and a cold air mouth or inlet 9 open to the atmosphere. The mouth 9 is controlled by the butterfly valve 10. The stem 11 of the valv'e 10 is arranged in suitable bearings in the walls of the inlet 9, one end extending for connectlon to the operating lever and the other for connection hereinafter described.

The fuel reservoir or bottom body member 12 fits into an' annular groove 13 on the under side of the intermediate body member 1. The fuel reservoir has an opening in its bottom adapted to receive the reduced threaded portion 14 of the body member 1 and is clamped against the shoulder thereof by the nut 15.

The body member 1 is provided with a fuel inlet passage 16 connected to a suitable supply pipe 17 by the coupling 18. The fuel inlet passage is controlled by the valve 19 arranged within the casing 20, the valve projecting downwardly through the bottom of the easing to 'coact with the lever 22 of the float 23.

.he float 23 is pivotally mounted at 24 on an arm 25 projecting from the tubular portion 3 of the body member 1. The reservoir is provided with a drain valve 26.

A tubular nozzle member 27 rojects upwardly Within the tubular portion 3 of the body member 1 and is connected with the reservoir by means of the fuel passage 28. The fuel nozzle 29-isprovided with a stem 30 having a longitudinal passage 31 therein with traverse openings 32 communicating with the fuel feed passage 28. The stem 30 threaded into the lower end of the tubular portion 3 of the body member 1 (see Fig. III). This provides means for adjusting the nozzle. The nozzle and its stem are, in the structure illustrated, shown as being formed of separate members, which is a convenience in manufacture. The nozzle stem is provided with a, packing gland 33 threaded upon the lower end of the depending portion of the body member 1. The body memher 1 is provided with an annular valve seat 34 supported in an elevated position relative to the body member 1 by spaced bridge portions or supports 35 and has a central port 36 through which the air passes to the mixing chamber 37. This mixing chamber 37 is, in the structure illustrated, formed with the top member and depends from the top Wall thereof opening into the discharge 38 of the carbureter, the discharge being con trolled by the throttle valve 39. The mix-' to the priming valve, as will dependmg portion 43 so that air may circulate from the inlet passage 7 about the same and pass downwardly around the valve seat member 34- and upwardly through the port 36 thereof to the mixing chamber.

When heated air is supplied to the carbureter the mixing chamber'is heated thereby. The lower edge of the mixingchamber fits into the shoulder 40 of the valve seat member. Y

The suction actuated member 41 seats on the valve seat member and is automatically actuated by the air passing to the engine .and constitutes a mixing chamber valve.

This suction actuated member 41 has a carbureting chamber 42 therein and a tubular slidably' embracing the nozzle member 27 so that the nozzle member constitutes a guide for the suctionactuated member and the nozzle delivers centrally to the carbureting chamber. The tubular portion of the suction actuated member is provided with a conical valve 44 coacting with the nozzle member and constitutes a -valve for the carbureting chamber. Air inlet openings 45 are grou ed about the nozzle member. The needle uel valve 46 is carried by the suction actuated member and projects. into the fuel-nozzle.

The carbureting chamber top piece 47 is supported 1n a spaced relatlon to its bottom portion to provide an annular slot-like discharge orifice or opening 48 for the .carbureting chamber. With the parts thus arranged when the suction actuated member islifted from its seat an annular unobstructed inlet port is provided for the mixing chamber. The carbureting chamber-delivers into the air passing this annular port at the periphery of the valve through the slot-like annular discharge port of the carbureting chamber, so that the carbureted air is discharged in a manner to be most effectively mixed with the auxiliary air passing to the mixing chamber.

The annular valve for the carbureting the needle valve projects into the fuel nozzle the fuel is discharged through an annular port centrally of the airinlet port of the mixing chamber so that the fuel is evenly taken up by and mixed with the air in the carbureting chamber.

The suction actuated member is with a dash pot plunger the cylinder 50 formed in in the mixing chamber provided 49 coactlng with a-cross'piece 51-. 37. By locating the dash-pot of the suction actuated member inthe mixing chamber it is subject to all variations of air pressure therein due to throttle or engine control and the running conditions otthe engine, which renders the suction ace tuated member very sensitive and quick acting and'quickly responsive to the throttle control and the running conditions of the engine.

Where the dash-pot is subject to atmospheric air pressure or to any air pressure other than that of the mixing chamber there is, under ordinary running conditions, a constant variation between such air pressure and that acting upon the suction actuated member thereby preventing" evenness in the movement or action of the suction actuated member under the varying suctions or degrees of vacuums in the mixing chamber. For example, if the dash-pot is subject to atmospheric air it is held toward its seat thereby at all times, and a greater suction is required for removing the valve from its seat than would be required if it were located in the. mixing chamber, and where a liquid dash-pot is provided the same variations occur. When, however, the dash-pot is in the mixing chamber and subject to the variations of air pressure therein these conditions are overcome and the suction member is very sensitive and ou'ick in its action.

A further advantage of arranging the dash-pot in the mixing chamber is that it is easy to locate it so thatit constitutes an effective guide for the air actuated member. Further, it is entirely inclosed and cannot be distorted by carelessness when the carbureter is assembled in an automobile or from accidental blows or the like while in use.

A still further advantage is that where the dash-pot is open to atmospheric air it is likely to draw in dust and dirt and become clogged thereby. l/Vhen located in the mixing chamber, any dust that enters the mixing chamber with the incoming air is not likely to pass to the dashpot, but is, owing to the velocity of the air, drawn past the dash-pot into the manifold.

A still further advantage is that when positioned within the mixing chamber it is subject to the vapors therein so that in practice it is effectively lubricated. T his accomplishes a double purpose,that of prevent, ing wear and friction and. further, the moisture forms a suitable packing so that a free sliding fit may be had between the parts without objectionable leakage past the plunger. In hon-practical use of the structure has demonstrated that the action is very superior to that instructures in which the (lash-pot is subject to atmospheric air or to structures in which the daslrpot is oi the oil or liquid type.

To prevent the return oi the valves itieingj unduly retarded we provide a vent passage 52 controlled by the check ball valve 53. On the upward movement of the suction attuated member this check valve .53 seats so that the desired cushioning effect is secured. ()n the return movement the valve opens so that air is admitted to the dash pot cylinder thereby preventing the suction actuated valve member being hung up and its quick action or return is provided for. This dash pot prevents chattering or fluttering of the valve member.

To furnish an additional supply of air to the mixing chamber when the engine is running at high speeds we provide an auxiliary valve 54: which controls the passage 55 communicating with the mixing chamber above the air actuated member. This auxiliary air inlet valve 5% is mounted in the valve seat member 56 threaded into the mouth of the passage 55 for adjustment therein.

The stem 57 of this auxiliary air inlet valve is guided in a cross arm 58 on the valve seat member. A spring 59 normally holds the valve 54 on its seat. \Vhen, however, the suction or vacuum exceeds a predetermined point this valve is lifted from I its seat against the tension of the spring admitting air to the mixing chamber above the suction actuated member, whichcontrols the fuel supply, as described. The valve seat member is adapted to be adjusted to regulate the tension of the spring 59, that is, it being threaded it may be screwed in or out to increase or decrease the tension of the spring.

A yielding stop 60 is seated in the socket 61 formed on the side of the body member 4 and is held yieldingly in engagement with the seat member by the coiled spring 62. The seat member is provided with a series of notches 63 with which the stop engages, thereby holding the adjustable valve seat member in its adjusted position.

With the parts thus arranged, the suction actuated primary air inlet valve is held to its seat by gravity only and the'valve is such that a practically uniform vacuum is maintained in the mixing chamber throughout the scope of the movement of such valve and the fuel valve is actuated with it. The seating spring of the suction actuated auxiliary air inlet valve of such tension that the auxiliary valve is actuated only after the primary inlet valve is opened and thus proper propoitioning oi? air and fuel at the higher speeds is secured.

To facilitate starting we provide a prim: ing device comprising a fuei passage 6% formed through one oi. the valve seat sup ports 35 and opening into the mixing chamber above or on the inner side of the mix-- ing chamber valve.

It fuel tube 65 depends into the reservoir beiou the normal incl ievei thereof and coin 'stitutcs an extension oi the fuel i iausagggc li-i.

This fuel tube is, in the structure illustrated, curved around the tubular part 3 of the body member 1 so that it does not interfere with the operation of the float. A conduit or passage 61 is arranged to deliver above the throttle vavle 39 (see Fig. III). The passage 64 and the conduit or passage 64 are controlled by the rotary valve 66 having a transverse'fuel port 67 therein and a longitudinal port or passage 68 which opens into this fuel port and into the air inlet chamber of the carbureter below the mixing chamber valve seat and into the delivery port 68' which opens into the conduitbc when the primer valve is open. The priming valve is shown in Fig. III in its open position, al-

though during the normal running of the engine it is closed. To start the engine the valve 66 is opened, which permits air to be drawn through the passage 68 and mixed with the fuel drawn through the passage 67 thereby providing a rich initial or starting mixture. If the throttle valve delivered mainly above the throttle valve and it will be noted that the conduit is positioned so as to secure the aspirating eli'ect of the air passing the throttle when 1t is in the position shown by dotted lines. The suction of the engine, however, actuates the automatic suction actuated valve, promptly supplying the proper mixture so that the primer valve can be turned off. It can be turned off gradually as the engine warms up, if desired.

A stop pin 69 projecting from the primer valve through the slot 70'limits the movement of the primer valve.

For convenience in operation the primer valve is connected to the means for operating the cold air inlet valve 10. This connection, in the structure illustrated, consists of a tongue 71 on the stem 11 projecting into a slot 72 in the outer end of the priming valve. The valve 10 has a lost motion connection to its stem, the valve being provided with hub portions 7 3 through which the stem is arranged, the central portion being slotted at 74 to receive the pin 75, thus providing a limited lost motion connection between the valve audits stem, see Figs. IV and V. A spring 76 is connected to this pin and the valve and normally supports the valve on the stem so that the end of the slot 77 normally engages the pin. This permits the turning of the stem after thevalve 10 is closed and the connections'for the primer are positioned so that the priming valve is opened after the air valve is closed, thus cuttitng oil the cold air supply when the priming valve is in use. This arrangement also has the further advantage of utilizing a single operating connection or means for the primer and air inlet valve.

This operating connection cpnsists of the is closed or substantially closed theprnning mixture is lever 78 pivoted at 79 in a housing or casing 80 having a peripheral slot 81 through which the lever projects. The lever 78 has an arm 82 connected by the wire or red 83 to the arm 84 on the valve stem 11. This rod is disposed through a housing tube 85, one end of which is supported by the clamp 86 on the carbureter body and the other by a block 87 adapted to fit into an opening 88 in the walls of the housing, the ends of the block being slotted to engage the wall, see Figs. IX and XI.

A detent 89 is provided to coact withthe segment 90 on the lever for holding the lever in its adjusted position. The detent is actuated by the U-shaped spring 91 sup ported by the detent pivot 92. The housing 80 is adapted to be mounted on a steering post and for convenience in mounting is provided with a slot 93 adapted to receive the notched end 94 of the securing strap 95. The other end of this strap is provided with an end piece 96 having a threaded bore for the screw 97. The series of spaced notches forming a series of lugs 94 so that its end can be cut off to fit it to the particular post to which the housing is to be attached. In attaching the notched end is cut oil so that the desired lug may be engaged with the housing. The notched endis inserted in the slot 93 and given a half turn to engage the lugs and is then drawn up by means of the screw 97. The housing plate 98 is removably secured by means of tihe screws 99 so that this can be conveniently one.

. The housing is provided with suitable in-v dicia indicating the starting position, hot air position and cold air position of the lever.

In the modification shown in Figs. XIII and XIV the housing 100 is adapted to be attached to the instrument board of a motor vehicle, the housing being seated in slot 101 formed in the board to receive it. The lever 102 is pivoted at 103 in the housing and is extended through a slot 104. A detent 105 is provided for the-lever and the housing has-suitable indicia indicating the positions of the lever.

A stop pin 106 limits the throw of the valve stem 11. The throttle valve 39 is pro vided with an operating lever 107, the operating connections for the lever not being illustrated as they form no part of our present invention,

We provide a drain tube 108 so that the fuel may escape should the carbureter become floodedthrough inoperativeness of the valves or other cause.

We have illustrated and described our improvements in one form in which we have embodied the same in practice. We have not attempted to illustrate or describe various modifications which we contemplate strap is formed with aas we believe the disclosure made will enable those skilled in the art to which this invention relates to embody or adapt the same as conditions and particular requirements may dictate. We desire, however, to be understood as claiming our improvements specifically in the form illustrated as well as broadly within the scope of the appended claims.

The valve control features described herein have been made'the subject matter of a divisional application, filed April 10, 1916, Ser. No. 90242, and the priming or starting features described herein have been made the subject matter of a divisional applicati'on, filed April 10, 1916, Ser, No. 90,241.

Having thusdescribedour invention, what we claimas new and desire to secure by Letters Patent, is:

p 1. In a carbureter, the combination of a chambered body provided with an annular valve seat, the chamber above said seat constituting a mixing chamber, a suction actuated. member coacting with said valve'seat and constituting a mixing chamber valve and providing when open an unobstructed annular port, said suction actuated member being provided with a carbureting chamber having an annular delivery orifice delivering to said mixing chamber at the periphery of the suction actuated member, a fuel nozzle disposed to deliver centrally to said carbureting chamber, an annular carbureting chamber air inlet valve carried by said suction actuated member and surrounding said nozzle providing when open an unobstructed annular air inlet port for said carbureting chamber, a fuel valve carried by said suction actuated member extending into the debureting chamber,

livery orifice of said fuel nozzle providing an annular fuel port delivering to said carbureting chamber centrally of its said air inlet port, an automatically actuated auxiliary air inlet valve delivering to said mixin chamber between said mixing chamber and throttle valves, a sprin for holding said auxiliary valve normal y on its seat, and means for adjusting the tension of said spring.

2. n a carbureter, the combination of a chambered body provided with an annular valve seat, the chamber above said seat constituting a mixing chamber, a suction actu ated member coacting with said valve seat and consituting a mixing chamber valve and providing when open an unobstructed annular port, said suction actuated member being provided with a carbureting chamberhaving an annular delivery orifice delivering to said mixing chamber at the periphery of the suction actuated member, a fuel nozzle disposed to deliver centrallyto said caran annular carbureting chamber air inlet valve carried by said suction actuated member and surrounding said nozzle providing when open an unobstructed annular air inlet port for said carbureting chamber, a fuel valve carried by said suction actuated member extending into the delivery orifice of said fuel nozzle providing an annular fuel portdelivering to said carbureting chamber centrally of its said air inlet port, a throttle valve, and an automatically actuated auxiliary air inlet valve delivering to said mixing chamber between said mixing chamber and throttle valves.

3. In a carbureter. the combination of a chambered body provided with an annular valve seat, the chamber above said seat constituting a mixing chamber, a suction actuated member coacting with said valve seat and constituting a mixing chamber valve and providing when open an annular port, said suction actuated member being provided with a carbureting chamber delivering to said mixing chamber, a fuel nozzle disposed to deliver to said carbureting chamber, an annular carbureting chamber air inlet valve carried by said suction actuated member and surrounding said nozzle providing when open an annular air inlet port for said carbureting chamber, a fuel valve carried by said suction actuated member to coact with said fuel nozzle, a throttle valve, an automatically actuated auxiliary air inlet valve delivering to said mixing chamber between said mixing chamber and throttle valves, a spring for holding said auxiliary valve normally on its-seat, and means for adjusting the tension of said spring.

4:. In a carbureter, the combination of a chambered body provided with an annular valveseat, the chamber above said seat constituting a mixing chamber, a suction actuated member coacting with said valve seat and constituting a mixing chamber valve and providing when open an annular port, said suction actuated member being provided with a carbureting chamber delivering to said mixing chamber; a fuel nozzle disposed to deliver to said carbureting chamber, an annular carbureting chamber air 1nlet valve carried by said suction actuated member and surrounding said nozzle providing when open an annular air inlet port for said carbureting chamber, a fuel valve carried by said suction actuated member to coact with said fuel nozzle, a throttle valve, and an automatically actuated auxiliary air inlet valve delivering to said mixing chamber between said mixing chamber and throttle valves. I

5. In a carbureter, the combination of a mixing chamber, a carbureting chamber delivering to said mixing chamber, a suction actuated member constituting a mixing chamber valve, 21 fuel nozzle delivering to said carbureting chamber, a carbureting chamber valve actuated by said suction actuated member, a fuel valve actuated by said suction actuated member and coacting with said nozzle, a dash-pot for said suction actuated member disposed within said mixing chamber, a throttle valve, and an automatically actuated auxiliary air inlet valve delivering to said mixing chamber between said throttle and mixing chamber valves.

6. In a carbureter, the combination of a mixing chamber, a suction actuated member constituting a mixing chamber valve. and having a carbureting, chamber therein delivering to said mixing chamber, a fuel nozzle delivering to said carbureting chamber, a carbureting chamber valve carried by said suction actuated member, a fuel valve coacting with said nozzle carried by said suction actuated member, a throttle valve, and

an automatically actuated auxiliary air inlet valve delivering to said mixing chamber between the throttle and the point at which the carbureting chamber delivers thereto.

7. In a carbureter, the combination of a mixing chamber, a carbureting chamber delivering to said mixing chamber, a suction actuated member constituting a mixing chamber valve, a fuel nozzle delivering to said carbureting chamber, chamber air inlet valve actuated by said suctionactuated member, a fuel valve actuated by said suction actuated member, a throttle valve, and an automatically actuated auxiliary air inlet valve adaptedto deliver to said mixing chamber between the throttle and the point at which the carbureting, chamber delivers thereto.

8. In a carbureter, the combinationof a mixing chamber, a suction actuated gravity seating primary air inlet valve for said mix ing chamber operating to maintain a substantially uniform vacuum in the mixing chamber during the full-movement of said valve, a fuel feed regulating valve carried by said primary air inlet valve, a throttle valve, valve delivering to said mixing chamber between said throttle and primary air inlet valves, and a spring for holding said auxiliary valve to its seat until said primary valve is fully opened.

9. In a carbureter, the combination of a mixing chamber, a suction actuated gravity seating primary air inlet valve for said mixing chamber operating to maintain a substantially uniform vacuum in the mixing chamber during the full movement of said valve, a fuel feed regulating valve carried by said primary air inlet valve, a throttle valve, and a suction actuated auxiliary air inlet, valve delivering to said mixing chamber between said throttle and primary air inlet valves, said auxiliary air inlet valve being actuated only by suction sufficient to fully open said primary air inlet valve l0. In a carbureter, the combination of a a carbureting a suctionactuated auxiliary air inlet mixing chamber, a suction actuated primary air inlet valve for said mixing chamber operating to-maintain a substantially uniform vacuumin the mixing chamber during the full movement of said valve, a fuel feed regulating valve carried by said primary air inlet valve, a throttle valve, and a suction actuated auxiliary air inlet valve delivering to said mixing chamber between said throttle and primary air inlet valves, said auxiliary air inlet valve being actuated only by suction sufiicient to fully open said primary air inlet valve.

11. In a carbureter, the combination vof a suction actuated primary air inlet valve operating to maintain a substantially uniform vacuum during the full opening' of said valve,a fuel feed regulating valve operated by said primary air inlet valve, and a suction actuated auxiliary air inlet valve delivering between said throttle and primary air inlet valves, said aum'liary air inlet valve operating only under suction suiliicient to fully open said primary air inlet va ve.

12. In a carbureter, the combination. of a mixing chamber, a suction actuated member constituting a primary air inlet valve for said mixing chamber and provided with a carbureting chamber delivering to said mixing chamber, a fuel nozzle delivering to said carbureting chamber, an annular carbureting chamber air inlet valve carried by said suction actuated member and surrounding said nozzle to coact therewith, aneedle fuel valve carried by said suction actuated member to coact with said fuel nozzle, a throttle valve, a suction actuated auxiliary air inlet valve for said mixing chamber delivering thereto between its said primary air inlet valve and said throttle valve, and means for holding said auxiliary air inlet valve closed until said suction actuated member is actuated to open the said valves carried thereby. 13. In a carbureter, the combination of a mixing chamber, a suction actuated member constituting a primary air inlet valve for said mixing chamber, a fuel nozzle, an annular air inlet valve carried by said suction actuated member and surrounding said nozzle to coact therewith, a needle fuel valve carried by said suction actuated member to coact with said fuel nozzle, a throttle valve, a suction actuated auxiliary air inlet valve for said mixing chamber delivering thereto between its said primary air inlet valve and said throttle valve, and means for holdin said auxiliary air inlet valve closed until said suction actuated member is actuated to open the said valves carried thereby.

valve, a throttle 14. In a carburetor, the combination of a mixingchamber, a fuel nozzle disposed so that it is Slll)]8 3i3 to the action of variations oi air pressure within said mixing chamber and to the action of the air current passing thereto, a suction actuated primary air inlet valve'fcr said mixing chamber, a fuel valve actuated by said primary air inlet valve, a suction actuated auxiliary air inlet valve delivering to said mixing" chamber between said throttle and primary air inlet valves, and means for retaining said auxiliary air inlet valve on its seat until said primary air inlet and fuel valves are opened.

15. In a carbureter, the combination of a mixing chamber, a fuel nozzle disposed so that it is subject to the suction within said mixing chamber and to the current of air passing thereto, a suction actuated primary 

